I remember seeing a very different approach with a very similar goal in Vietnam.
In Hanoi, many houses have a small greenhouse-like glass structure on the roof. The greenhouse has a chimney. When the sun is shining, it gets hot in the greenhouse and the hot air escapes through the chimney. A hatch through the roof into the greenhouse draws new air from below, essentially creating a passive, sun-powere air-flow through the whole house, bottom-to-top. Usually some windows on ground level are left open to let air in.
People tend to confuse the passivhaus idea with other energy efficient methods. The passivhaus idea is that if the building has sufficient insulation and is air tight, you can use the air from the heat recovery ventilation system to do any required heating cooling. This simplifies the mechanical part of the system.
As a result, such houses are very well ventilated when it is cold outside. Mould is not a problem. The potential problem is instead excess dryness in places where it gets very cold.
The dryness problem normally only occurs if the air change rate is higher than the recommended 0.3. In large buildings this requires rather sophisticated ventilation systems. There are also heat exchangers that recover humidity.
In fact I found that it seems ERV (recovers heat & humidity) is more common than HRV (recovers only heat) these days. Possibly for the simple reason that ERV suffers less from the exhaust icing up.
I can confirm the excessive dryness problem. My gf moves to a passivhaus a few years ago, and I had real trouble with cry eyes during the night. After a year, I sort of adjusted, but it definitely doesnt feel very healthy.
You just need to cook more pasta: large pots of boiling water. :)
More seriously: a very airtight house, which is generally desirable, does need a properly balance HVAC system. In some climate zones this means perhaps having a humidifier and in other zones a dehumidifier.
Most people only think about furnaces and air conditioners when considering HVAC, but those mostly deal with temperature. Humidity has to be considered separately, often by different equipment.
I am guessing in many cases, there is no money left for humidifiers. You start out with the idea that you want to build a passivhaus. But you still have a limit on how much you can spend. So all the ventilation stuff is being installed, and the humidity control is being skipped. Which leads to each and every individual apartment considering their own humidifier, which probably pretty much kills the energy-efficientcy-idea that started the whole thing.
At least that is what I observed in my limited small world.
Humidity below 30% is cruelty.
it becomes dry inside no matter how you ventilate or heat, if it happens through a vent system with heat exchanger, there are built-in humidifiers for these
There is a second problem in cold places that comes from the humidity you add on the air intake. The heat exchanger has to deal with that moisture freezing on the exhaust side. There are methods for doing this but none of them are ideal.
There's a countermovement, the "Pretty Good House" idea ( https://www.greenbuildingadvisor.com/article/pretty-good-hou... .) It has the goals like "simplicity" and "avoiding diminshing returns" (the 80-20 rule: 20% of the work gets you 80% of the improvements, in this case.) It avoids certification and excessive rigor. (One article about it mentioned the split between Passivhaus and Passive House. As I recall it was over the amount of shading from one southern tree.)
My point, if any, is that it's not "Passivhaus or nothing."
Oh thank god. This is the approach I had when I built my house. This is IMO the most desirable territory: Just try to maximize the easy assets of wind and light using traditional methods, and add in modern insulation.
Few(???) architects and zero builders seem to understand light/wind/circulation like people apparently intuitively did 200 years ago. You might be better off with the average curious engineer designing a house after reading a couple books than the average architect. Everyone is astonishingly lazy, even mansions around here have terrible light/circulation problems. But if you care, you can totally design a good one yourself that has very low operating costs (our electric bills are 50-80 a month in a 2200sqft house. We use maybe 3 cords of wood a year, but that's very approximate).
It does not take a lot of work to design a house, especially if you want to build an efficient Colonial style. My goals were simple: Build something that appears traditional, maximizes light and airflow and wood burning heat. Think about ventilation passageways as the windows and doors, and think of the wind as coming and going. Since heating is easier than cooling (we built in no AC system and zero ducting), make your ceilings taller.
A little wood stove (Vermont Castings Encore) heats the whole thing. Spray foam insulation in the walls (plus fiberglass), tall ceilings, and modern windows (lots of them) is all you need.
> Few(???) architects and zero builders seem to understand light/wind/circulation like people apparently intuitively did 200 years ago. You might be better off with the average curious engineer designing a house after reading a couple books than the average architect.
Any book recommendations, especially around wind/circulation?
I realized that the cupola on my 1840's house growing up, this was it's function. Wind pulls air through, which pulls air up into the attic, which cools the first and second floors.
Then read The Timeless Way of Building and perhaps A Pattern Language
Then Get Your House Right, or a condensed (...in a way) version is Drawing for Architecture by Krier.
Hmm there are probably others I cannot recall right now, but those are a great start.
Both definitely have their place, the pretty good house is an achievable goal even if you're retrofitting and gets you most of the benefit. The passivhaus pushes the envelope, figures out what's attainable, & develops new techniques & appliances that can trickle down.
Just bought a brand new house here in the UK and the house has a SAP designed footprint of 85kw/m2/a compared to the Passivhaus standard of 15kw/m2/a.
Unfortunately I have no choice. Unlike in Germany I don't get to buy the land and pick the builder. The two come bundled in the UK. And will do until we get political change that breaks up the building oligopoly.
Here in NL the two are also usually inseparable (you buy a house from a large project, typically 100+ homes/apartments, sometimes even 1000+). But, just looking around our two countries, it just seems requirements in the UK must be lower. The average house just seems less well built.
I was thinking on buying a land in the UK and buy a prefab/kit house that cost about £2000-£3200/sqm . Did you consider that option? Why did you reject it?
This can happen in DE and AT as well, especially in expensive regions.
Developers simply have the money/the better leverage by buying in bulk. Then there are developers that simply sell you the (tiny) lot for a premium, and let you choose between something they arrange, or building yourself. And the good lots are always gone long before the project is announced anyway.
Sadly it looks like that idea is not that sustainable. A Passivhaus (well, every current Niedrigenergiehaus, actually) is a very complicated matter and comes with some intrinsic problems:
> Airtight design resulting in draught free construction
That airtight design leads to problems with mold if you have any cold spots. These spots can occur due to construction faults, material faults, or any kind of acquired damage. For instance, you might not even notice that your windows do not shut exactly as they were supposed to after a few years.
In the end, the repair of such a complicated design is again very complicated (especially after a decade or two have passed and technology has again advanced), expensive, and error-prone.
So for me, I'd rather prefer to take an existing, robust and dry building, insulate it somewhat (especially roof and windows) and put in a regenerative heat source (wood, electric) but not to focus too much on the actual energy needed.
More important is properly maintained. People tend to forget to change filters. Those are a prime breeding ground for mold, and your central ventilation distributes the spores throughout the house.
That's why people should change the filter and have a yearly inspection, just like for cars.
But the filter is on the ingoing side and not on the outgoing side, so no moisture from the inside can aggregate there. Only the humidity from the outside but we've never had problems with that.
My HRV has filters for both inbound and outbound airflow. I do change my filters regularly, but even in the rainy Pacific NW I haven never seen any mold growth on either filter, and I have an RPi logging air quality data with a decent sensor, so I can see my PM2.5 and PM 10 are both near-zero.
Because we stood in front of the same decisions this year, I can only recommend to use wood not stone as building material. And wood fiber insulation. Building techniques in that area are pretty advanced. (At least I hope so, let's talk about it in twenty years again :D )
I think this has already been addressed by the sibling comment to my question. Insulation does not have to impermeable. Its purpose to prevent the loss of air carrying heat with it, not the transfer of moisture/humidity.
A good way to solve that problem is building a house made of wood which has no diffusion barrier and additionally putting clay on the inner walls. There are a couple of interesting solutions.
And the ventilation system takes care of the rest of humidity, especially after taking a shower or when cooking.
I don't understand why we don't mandate stricter energy efficiency for new buildings. Why is it still legal to rely on fossil fuels for heating for example?
An example given in this thread was that current Passivhaus practices specify that embodied energy (one time energy cost that goes into the materials and the construction) be no larger than 50 years of operating energy costs. Stricter energy eficiency means reducing operating energy costs. Reducing operating energy automatically reduces the allowable embodied energy budget. This limits how much energy you can spend upfront to improve efficiency with current techniques. We need better techniques. Increasing the number of years doesn't help that much, as it can lead quickly to a higher energy TCO than a conventional house, so why bother.
Remember it's the energy TCO (total cost of ownership over project lifetime) that captures the full environmental impact of the house, as every MJ of energy - regardless if embodied or operating - translates into a known quantity of GHG emmissions, particle pollution, and so on.
In a pleasant surprise, spending energy later (in energy costs, rather than embodied) is better than spending it today for the environment! Energy produced in the future will surely emmit less GHG and pollution than today (better techniques!), and the GHG will dwell less time in the athmosphere, so less compounding effects on the total temperature rise that we'll have at the end of this century.
If you care about the environment, you have to consider the energy TCO.
The actual implementation is left up to individual countries. In my country, Lithuania, it means from 2021 all new houses require insulation to be at the same level as Passivhaus, and buildings to obtain the majority of their energy from renewable sources (so most new houses will have PV installed). It gets cold here in the winter (-20c isn't uncommon), so if it can work here, it can work pretty much anywhere in Europe.
As can be expected this will push the price of new builds up, but the benefits are a more comfortable and healthy environment (I grew up in drafty & moldy houses in the UK) and lower energy costs (grid-tied PV installations, without a battery, usually pay back in 7 to 10 years, after which they provide free energy for the life of the system).
Edit: I should mention the prices will not rise in a significant way. Materials for the structure/building envelope are usually a small part of construction costs, and those required for Passivehaus are not expensive or hard to obtain. Of course propery developers will complain, as the extra cost will come out of their profit margin :-)
The obvious answer is cost. How long do you want young people to live with their parents to save up for the efficiency improvements you propose? How much longer should their mortgage be? How many people become unable to afford one at all and have to live on the street?
I have a friend who is a building a house by himself. I think that's really cool. If you set standards too high that wont be possible.
Finally bureaucracy sucks. Even an "obvious" regulation that all houses follows like "your house has to have a roof" has the potential to become seriously annoying if you have to get an inspector who is only available in a month and only on Mondays 9-10, to take a look and write a statement that your house indeed does have a roof.
The sad thing is the cost is recouped in energy savings very quickly, and there's never a better time to add inexpensive subslab insulation than right before you pour the slab.
I feel like housing cost is driven more by land use policy than by efficiency standards (or building codes.) This must be something people have researched though.
In the UK the plan is to eliminate the use of fossil fuel based heating in new homes by 2025, and convert existing homes by 2050[0].
Apparently "14% of UK greenhouse gases come from our homes, a similar level to emissions from cars. In major cities gas boilers are also a main source of nitrogen dioxide emissions."[1]
Having researched this recently for a potential house purchase, there's a need for innovation before electric heating becomes a reality.
The standard is still storage headers and other wall mounted electrical heaters. I remember those from childhood, and how happy we were to switch to gas-fired central heating.
There are electric boilers which can power a hot-water based heating system; they are substantially more expensive to operate than current gas boilers (due to the UK price differential between gas and electricity).
My most favoured approach is an air source heat pump, and larger radiators/underfloor heating to make use of the lower temperature heat source. More expensive to install and run than a gas fired central heating system.
Perhaps in the house after next, this will be standard - or I might even be able to buy a Passivhaus.
Also had a look at electrical heating options again recently. Everywhere I've lived that burns fossil fuels to generate heat has been plagued by costly maintenance. At my current place, not unique to these issues, I've now spent an average of £175 a year on repairs (£1230 total over 7 years). In contrast, I lived for 10 years in a place with electrical heating and never had to do any maintenance whatsoever. Certainly gas is cheaper to run in terms of the price per unit of energy consumed, but if you factor in the maintenance and the hassle factor of taking time off to be in for the repair people, then I'm not convinced there's such a big difference. If you ask a boiler repair person about switching to electricity though, they'll say they strongly recommend against it, but part of me wonders if that's because they have a vested interest in keeping people using the high maintenance options. I used to joke that the only reliable thing about my boiler was the revenue stream it generated for the repair people.
Underfloor electrical heating is apparently a lot more efficient than radiators, e.g. because you only need to run them at a much lower temperature. If you combine with things like ground source heat pumps and solar panels, the electric heating proposition looks a lot more appealing.
That said, the conclusion I came to is that for an old place that doesn't otherwise need major work, it just isn't worth the expense of making the switch. It might be that if I were to move somewhere that needed a complete refurbishment anyway, then I would. Even then, with most homes, at least in cities like London, being flats rather than houses, then things like solar panels and heat pumps become much more difficult if not impossible to arrange.
There is a new development behind me that is all air-source heat pumps however they are very expensive houses. New flats in the area are nearly all using storage heaters.
Necessary footnote: the age of the average dwelling in the UK is 75 years. (I live in a ~200 year old apartment. It's not particularly unusual in being of that age.)
Yes, its all well and good looking at things like a Passivhaus for a new build, but in places like the UK there are very few opportunities for new builds, given homes have historically been built to last for decades or centuries rather than be torn down and rebuilt every few years. As a result, 76% of UK housing stock is more than 40 years old and 20% is more than 100 years old[0]. Even after the mass destruction of housing during the Second World War, some of the prefabs (built quickly and only supposed to last 10 years[1]) are still in use over 70 years later (in some cases ironically now listed buildings[2]).
Also: AIUI there's no VAT due on new build properties on green field sites (of which there are very few),but redeveloping brown-field sites attracts VAT charged at 20%. Which is frank insanity in terms of public policy on a small, crowded island, but ...
There was going to be a net-zero energy standard in California for new houses, but it's not clear to me what happened. Apparently they decided that solar panels shouldn't generate more power than needed by the house? This FAQ has an answer that doesn't seem to say yes or no:
As far as I understand, buildings (walls, ceiling, roof, etc.) mostly get to A. A/2 is achieved with photovoltaic panels on the roof, and A/3 with also thermal solar.
In some countries there are mandatory rules for new buildings. Most experts would tell you that they failed spectacularly. For a time styrofoam was recommended. Today you have difficulties to dispose that shit again.
> Why is it still legal to rely on fossil fuels for heating for example?
Because there are few alternatives. You can use wood, but that comes with its own problems.
Interesting that this comes up now in 2019. I'd say, while a Passivhaus is not the standard in Germany yet, you can simply go and buy one, like you can choose a special version of a car and simply order it. Passivhaus is still cool, but nothing extraordinary from the future.
Not from the future, but for the future: In 30 years from now (2050) we should be carbon neutral in order to have a shot at the 1.5° C target. Average building lifetime is >30 years. So in my opinion it would be irresponsible to build anything else than a passive house or a zero energy building today.
Many governments, such as the EU have decided Zero Energy Buildings as a target for 2020. Those are basically passive houses with PV systems. Hence they produce the same amount or a surplus of energy as is being used throughout the year.
That is simply wrong. The passive house standard requires ventilation systems with highly efficient heat exchangers. This makes for good air quality. The massive thermal insulation ensures that no condensation occurs in the interior, i.e. no mold problems.
A common problem, however (esp. if inexperienced planners design the house) is too dry indoor climate in winter. This happens if air change rates are too high and no humidity is recovered.
The regulations for Passivhäuser (or houses with the respective efficiency rating) in fact require a ventilation system with heat recovery (since the otherwise necessary open-the-windows-like-a-savage-system wastes too much energy).
These nowadays come typically with moisture recovery (which arguably not always works well enough, depends on how much you still need to heat).
Exactly, my first impression when seeing the design is that it looks like a massive ticking mold timebomb.
If at any point in the building's lifecycle the thick glass wool insulation is wetted (such as through a building/materials fault, an accident or some very slow process), a hidden mold problem will start developing within the walls. By the time you notice it (strange smell, irritation in lungs or eyes), it will be too late and the most economical solution will be to demolish the whole house and building a new one.
People who live in cold and wet climates know this all too well. OTOH, thick insulation is not required in warmer climates.
There's nothing wrong with over-insulating (although at a certain point it is no longer economical), but you need to ensure the house is ventilated to prevent mold.
You also need to ensure you choose the correct building materials, so they can ventilate themselves. Modern building science says there should be a continuous airtight wrap around a house with insulation either side. The interior insulation ventilates to the inside, and the exterior ventilates to the outside. What you don't want is multiple airtight layers as that could cause it to become moldy inside the layers.
Passivhaus houses will almost always have a heat-recovery ventilation system. These will bring in fresh air and take out stale air - like a bathroom fan. But they also exchange heat from the outgoing to income air in the process. Typically 80%+ of the heat is recovered (you can get systems that are 95% efficient). They run at a low speed so consume minimal electricity (typically under 100W for small houses) and don't provide a noticeable draft like air conditioning or forced-air heating. They have filters to prevent pollen and other contaminants from entering your house, so for allergy suffers they are a big plus.
I live in a cold climate in an apartment built in 2015, which is well insulated and has this system. Even though it has been below freezing (currently 8c) outside, we haven't yet needed to turn on our heating because of how well the building is insulated. We do actually have a typical vented bathroom fan, but everything else (kitchen hood and dryer) are unvented, so we keep all that heat inside.
Where did you learn about modern building best-practices? I just bought my first single-family home and am excited to slowly transform it into a comfortable-and-efficient modern building. But I'm finding it a little difficult to penetrate this new-to-me space and would love to find some more-complete resources.
My random web-crawling has certainly been moderately productive, but it's slow and I can't help but feel that I'm not being adequately exposed to a reasonable breadth of topics.
In 2016, I moved from California to Rhode Island to build a Passive House. It was completed and certified by PHIUS, the American PH standards organization, in 2017.
There are even two subsequent standards: the Nullenergiehaus (zero energy building) and the Plusenergiehaus, which is better by having the ability to generate more electric energy than it needs.
However, those buildings are not as amazing as they might look. The "better" the standard, the greater the effort. What people didn't really took into account was the energy needed to actually build the house is becoming very large. At this point it takes the same amount of energy (embodied energy, called grey energy in Germany) to erect a Passivhaus as it will need operating over the next 50 years.
Do you have a source for those figures? Given the very low energy usage of a passivhaus, 50 years worth of energy sounds like a good deal. But perhaps it would be more useful to compare like for like. How many kWh do we need to erect a passivhaus and operate is, vs a non-passivhaus?
I was also under the impression that many passivhaus implementations made heavy use of wood, and thus end up sequestering carbon for the lifetime of the building, but I don't know if that's mandated by the standard or just a preference of some builders.
> At this point it takes the same amount of energy (embodied energy, called grey energy in Germany) to erect a Passivhaus as it will need operating over the next 50 years.
That doesn't mean much since it takes less and less energy to 'operate' the house. For energy-positive housing it by definition takes more energy to build the house than to run it for a single day since the house is a net energy producer. Leave that fact out and use it as a headline and you can guess the reactions.
What is important is the trade-off between effort spent in creating energy-efficient infrastructure - whether it be housing or industry or roads or whatever - versus the expected returns, the projected lifetime, the means to distribute energy and more. Having an energy-positive suburb won't gain much if there are no means to transport the energy to the city centre or industry where it is needed. Insulating against -20° winter temperatures does not make sense on the Canary islands (and no, insulation is not the same as thermal buffering which can be used to lower inside temperatures during hot days, viz. adobe constructions).
> At this point it takes the same amount of energy (embodied energy, called grey energy in Germany) to erect a Passivhaus as it will need operating over the next 50 years.
Is that because the build energy is so high or because the energy usage is so low? I mean, by definition the energy used by a zero-energy house is zero. Shouldn’t you compare the build cost to a conventional house’s energy usage?
Our home is currently constructed from wood. The price is not higher compared to stone/concrete solutions.
Simply building a house in Germany at the moment results in a passivhaus. We also added the ventilation system which wouldn't be necessary, but I like the system, needing not to open the windows in winter that often or at all.
> energy needed to actually build the house is becoming very large
Why is it becoming larger? I would have assumed that we would use less energy rather than more to build buildings nowadays given the advances in technology.
You need permanent ventilation, better heat insulation, better doors and windows etc. for this to work. You still have to plan for some way of heating so you cannot just leave that out. This in all takes more energy to build and maintain.
That said, I live in a passive house and we turn on the heating only when one of us is sick or when it gets really cold.
> You need permanent ventilation, better heat insulation, better doors and windows etc. for this to work.
For many houses the better heat insulation is mineral wool and or styrofoam. Transporting either of these must be significantly more energy efficient than brick. If I look at how some old buildings are built here I have to assume that was not energy efficient during construction just from how much more material was used.
Do you have a source that better insulation requires more energy? Especially the extra windows must be more energy efficient during production as well if you look at how they are manufactured. They only extra material is a third glass pane but for that you save on a lot of extra fittings compared to old windows.
I would really like a source on why you think there is more energy used for building the house. It's very counter intuitive.
That is not quite true. The relative share of the life-cycle impact of material increases, because total impact decreases. There are a couple of reviews that discuss this matter and normally find that total life-cycle impact is consistently lower. https://www.sciencedirect.com/science/article/pii/S036013231...
Air tightness can easily be a problem. Something gets wet and can never dry out. There is mold. The only solution is to dismantle the structure.
One problem with complex buildings is the limited average skill of the builders and variable quality control in the business. Building technology should take that into account.
Probably one reason is the volatile nature of the business - you have to hire anyone you can get because everyone else is building too at the same time.
So I guess if one were to "disrupt" construction, one would have to start from the financing...
Seems like there'd be a market opportunity to automate or at least create an assembly line for constructing the most at-risk parts of buildings. Or to make systems which might cost more in materials but assemble correctly with low skilled labor quickly.
I'm sure there's lots of this already going on. New houses built recently near me have all the walls delivered on a truck preassembled, but the skill and quality of the assembly teams from house to house has been interesting to watch from afar.
There is some interest at least here to avoid composites (combining different materials) and instead make for example the wall out of one material, just make it thicker so it can handle strength, insulation, sound proofing, breathing and other demands.
An alternative is to make sure that all materials are breathable and dryable. But even things like glues can be problematic.
I have seen houses that have been almost completely made out of pure timber (no glue!), nails, wool, clay and chalk. Some steel joiners. No glue. They don't even have regular paint in the rooms, it's clay with a hemp mesh inside and then chalk on top, or some such. I don't know how the bathroom was handled.
A more general learning we can take from Passivhaus building techniques is that habitable buildings should be designed to work in conjunction with the natural environment they inhabit, like they used to be before the era of cheap fossil fuels. But such site and solar-orientation aware design isn't today part of the practice of building mass produced homes, and absent forces that push that industry that way, things aren't likely to change.
> Some estimates suggest there are well over 50,000 Passivhaus buildings around the world. They have been successfully built in European climates, the US and Canada along with warm Asian climates where there is a requirement for cooling.
Yes but the amount of insulation required to meet the requirement is climate dependent. That means that the building methods for achieving the requirement might not exist yet in some places in the world.
Given that we should be carbon neutral in 30 years from now (2050) in order to have a shot at the 1.5° C target and given that average building lifetime is >30 years, it would be irresponsible to build anything else than a passive house or a zero energy building today.
I know it is a fringe case relative to the lifetime but I am curious how well the designs handle power extended power outages and say high ambient temperatures compared to other house types.
Thermal insulation helps to decouple indoor climate from the outdoor climate. It depends a bit on what kind of heat period you consider. When high ambient temperatures occur it will remain cool for longer indoor and night ventilation can be used to cool the house. The cold produced by the AC is also better trapped inside, ie used more effectively.
There has been a case of extended power outage in Germany due to heavy snowfall. I saw a report that showed how the indoor temperature remained almost constant for the first two days of the outage.
While not entirely "passive", houses built to the KfW 40 Plus standard in Germany are pretty close (without some of the inconveniences of a real Passivhaus)
In Hanoi, many houses have a small greenhouse-like glass structure on the roof. The greenhouse has a chimney. When the sun is shining, it gets hot in the greenhouse and the hot air escapes through the chimney. A hatch through the roof into the greenhouse draws new air from below, essentially creating a passive, sun-powere air-flow through the whole house, bottom-to-top. Usually some windows on ground level are left open to let air in.